Atrial flutter can cause false-positive ***ACUTE MI SUSPECTED*** interpretive statements

I first heard about this issue a couple of years ago in a webinar at the D2B Alliance website. Since then I have seen it several times in my own EMS system.

I also mentioned it when I commented on:

Review of Factors Associated With False-Positive Emergency Medical Services Triage for Percutaneous Coronary Intervention

According to that study the most common factors associated with false positives statements were:

  • A specific brand of one of three monitors used in the system
  • Sinus tachycardia
  • Missing lead recording on 12-lead printout
  • Atrial fibrillation
  • Female gender
  • Poor ECG baseline
  • A discussion ensues during

The authors make this important statement:

“Poor ECG baseline and failure to record all 12 leads for machine algorithm interpretation are false-positive associated variables that can be addressed by improved quality in field acquisition of 12-leads.”

It can’t be said often enough! That’s why I’m always harping on achieving excellent data quality!

The authors continue:

“Variables more difficult to address are sinus tachycardia and atrial fibrillation, which had a tendency to be wrongly interpreted by machine algorithm as acute MI.”

In response to that statement I made this comment:

“It would be interesting to know if they are including atrial flutter in with atrial fibrillation. Either way the message is clear. The specificity of the computerized interpretive algorithms is highest when a tachycardia is not present.”

The reason I questioned whether or not atrial flutter was included with atrial fibrillation is simple. Many times I have seen atrial flutter trigger a false-positive ***ACUTE MI SUSPECTED*** message on the LP12 but I can’t think of a time atrial fibrillation cause a false-positive statement (when poor data quality was not present).

Consider these cases that occurred in the past week.

Case #1

In this case the paramedic immediately realized the ***ACUTE MI SUSPECTED*** message was being caused by underlying atrial flutter. A “STEMI Alert” was not called from the field and the patient was not sent to the cath lab.

Case #2

This case was a little more difficult because 2:1 atrial flutter more difficult to recognize than 4:1 atrial flutter. It also must be said that this patient was “sicker” and presented very much like ACS. A “STEMI Alert” was called from the field and the patient ended up in the cath lab. No significant lesions were noted with angiography.

The point isn’t to blame the paramedic from the second case. A board certified emergency physician and a cardiologist both had to agree that this patient needed emergent angiography.

It’s easy to criticize individual paramedics especially when they’re from other EMS systems. What’s hard is to create quality improvement feedback mechanisms so that every call can be a learning opportunity.

There are two kinds of EMS systems in this world: those that make mistakes and those that have no idea whether or not they make mistakes (unless they receive a complaint).

Strive to be the former because anyone can be the latter.

5 Comments

  • Christopher says:

    Second ECG is tough! Rate and p-axis in II/III can lead you to 2:1 flutter. Also the T-waves are certainly strange looking. I think the only thing holding me back from a STEMI call is the rate on that one.

  • Christopher says:

    Another thing that a-fib/flutter can mess with is synchronized cardioversion. Resuscitation recently had a case where an ED used a Philips MRx set to sync through the pads and the R-wave detection kept picking up the fib/flutter waves as well, delivered a shock, caused R-on-T, v-fib…and thankfully a successful resuscitation.

    Sodeck GH, Huber J, Stöllberger C. Electrical cardioversion – misinterpretation of the R-wave. Resuscitation. 2011 Jan;82(1):135-6.

  • Mike Sherriff says:

    I too have had 2:1 A-Flutter read incorrectly as STEMI, on a Zoll.

  • speaking of a-flutter, when i review ekgs i’ve noticed the LP12s love to interpret VT as a-flutter.

  • Banery says:

    There always you want to a 740 problem during the installation.
    The MAC compatibility means that that Dub Turbo software
    can be powered by an iPad.

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EMS 12-Lead

Cardiac Rhythm Analysis, 12-Lead ECG Interpretation, Resuscitation
Comments
David Baumrind
All that wiggles isn’t Wellens’
@Gary, by all means, nitpick all you like. I agree with your assessment, and the post has been modified. Thank you for the feedback!
2014-08-30 17:28:16
Gary Huntress
All that wiggles isn’t Wellens’
Not to nitpick but is this really a "slightly leftward axis"? I and AVF are both positive. I put it at about +20 degrees, not leftward.
2014-08-30 11:49:35
Handsome Robb
87 YOM COMPLAINING OF CHEST DISCOMFORT AND DYSPNEA
CHF. 12-lead shows a sinus Tachycardia in the 120s with PACs, besides the anterior leads there's diffuse ST depression, the STE in the anterior leads can be explained by the LBBB, axis is good as well. I wish they posted the EtCO2 waveform so we could see but I'm assuming it's non-obstructive. The elevated EtCO2…
2014-08-30 08:08:22
Christopher Watford
“Bad heartburn” – 82 y.o. female without chest pain.
Brooks, Firstly, thank you for the warm welcome to the club. Secondly, the Glasgow algorithm's only published sens/spec for AMI is 51.6%/97.6% respectively (Tuscon STEMI Database). I've not been able to find any other publications. The GE Marquette 12SL algorithm has been widely studied, but is much older, and ranges in sensitivity from 48% to…
2014-08-29 16:50:14
CB
57 Year Old Male–Chest Discomfort
Given what he was doing (paint fumes on ladder painting) I would first question if the pain is reproducable. Yes his ekg isn't normal but looks like old inferior MI. And he is hypertensive. 02 a must. Def. would give ASA. First would give morphine and see how his cp and bp are. If still…
2014-08-29 11:37:25

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